SEWERAGE OF A SEASIDE TOWN. 783 



With regard to the cost of making the necessary pro- 

 visions for carrying out the system of sewage disposal by the 

 precipitation process I have described, 1 have got no such 

 details as Mr. Mansergh's Report furnishes with, respect to 

 his irrigation scheme ; and as I have not the time at my 

 disposal to get out such details for myself, I base my calcu- 

 lations upon the experience of Southampton, and offer them, 

 not as exact, but as showing — after a very large allowance is 

 made for errors — that precipitation by ferozone is a system 

 worth considering. 



The three necessities, as far as capital expenditure is 

 concerned, that are required for this system, are — the tanks, 

 means of discharging the effluent, and means for dealing 

 with the sludge. I cannot separate the expenditure at 

 Southampton upon tanks from that upon the ejectors and 

 the machinery ; but, taking the Melbourne sewage to amount 

 to 42 million gallons a day, the necessary tanks and machi- 

 nery of all sorts, and air and sludge mains, would cost (being 



20 times the cost at Southampton) £600,000 



To burn the sludge would require 80 additional 



destructor cells at a cost of 32,000 



Making a total capital outlay of. £632,000 



The yearly charges would be — 



Repayment of capital and interest £26,950 



Work at tanks and destructors, and superin- 

 tendence (being 20 times the cost at South- 

 hampton) 5730 



Ferozone, 6900 tons, at 60a- 20,700 



Making a total yearly charge of £53,380 



It will be noticed that, in connection with the yearly cost of 

 pumping for Mr, Mansergh's scheme, I have only taken half 

 what he allows, as I think, even with his machinery, the other 

 half might be saved by utilising the steam-generating j)Ower 

 of destructors. 



Now these figures show, with the reservation 1 have made, 

 that the necessary expenditui'e for the sewage disposal 

 works of Melbourne, as distinct from sewage collection, will 

 be £2,050,000 for doing it by irrigation, against £632,000 

 for doing it by precipitation, — a difference in favour of the 

 latter of over £1,400,000. The yearly cost of the irrigation 



